Gas turbines include a gas turbine having a combustor (DLE combustor) adopting a lean premixed combustion method (Dry Low Emission combustion method). In this combustion method, in a premixed combustion system combusting a premixed gas acquired by premixing fuel and air, the premixed gas is made leaner to suppress an amount of emission of NOx harmful to the environment. A tight regulation is imposed on the amount of NOx emission, and this regulation on the amount of emission leads to a limitation on a load range of fuel to be combusted and a limitation on a range of use of a burner. Therefore, the lean premixed combustion method is effective in that the range of use of a burner can be expanded in this way.
With regard to the gas turbine, from the viewpoints of prevention of global warming and effective use of resources, it is requested to use a byproduct hydrogen gas secondarily generated from a manufacturing process of a petrochemical plant etc. in addition to a natural gas that is a main fuel of the gas turbine.
However, the hydrogen gas has a faster combustion speed than the natural gas. Therefore, a burner combusting a fuel containing the hydrogen gas has a higher possibility of a flame entering a burner premixed gas passage (this phenomenon is referred to as “flashback”) and causing a burnout of the burner main body as compared to a burner combusting only the natural gas.
To solve this problem, JP 10-26352 A discloses a premix combustor for a gas turbine incorporating a flashback prevention technique. This premix combustor has a cooling flow path provided in the vicinity of a wall surface of an injection port (annular nozzle) of a premixed gas, and a coolant such as water is circulated in this cooling flow path to forma low temperature flame extinguishing region in the vicinity of the wall surface so as to extinguish the flame entering the inside of the injection port.
However, the premix combustor disclosed in JP 10-26352 A requires a large number of pieces of equipment such as a coolant flow path and a coolant circulation amount control means.